Secretary of State McCord reluctantly agrees to host a holiday party in the hopes of persuading senators in attendance to pass a treaty that requires countries to destroy landmines. Also, Henry tries to find evidence that the Senate Majority Leader exchanged information with the Russians.

Secretary of State McCord and her staff work with the Mexican government to extradite a Mexican cartel leader to a U.S. prison in an effort to diminish the opioid crisis. But after he escapes during transport and a journalist who secured a gloating interview with him while on the lam is murdered, Elizabeth’s urgency to find the leader escalates.

When a Russian dissident flees to the U.S. after contracting smallpox, Secretary of State Elizabeth McCord and retired U.N. Ambassador Kat Sandoval must work with Russian Foreign Minister Konstantin Avdonin to contain the outbreak.

Henry disagrees with the President and Elizabeth when they refuse to negotiate with terrorists for the release of an American CIA agent who was captured by the Taliban in Afghanistan. Also, Elizabeth tries to be supportive of Stevie, who is going through a difficult time.

Elizabeth is determined to continue to hold a human trafficking conference in Kyrgyzstan despite the inappropriate actions by a U.S. ambassador. Also, Elizabeth and Henry worry about Alison when she keeps coming home from college.

Elizabeth tries to fund an electrical grid in a Syrian refugee camp before riots break out in the country due to a lack of electricity and water. Meanwhile, Henry searches for Dmitri when he goes missing.

Elizabeth is involved in a car accident in Libya when she goes there to help negotiate an end to their civil war and must secure medical care for a gravely wounded local girl who was hit by Elizabeth’s chauffeured vehicle.

Season 4 begins with a diplomat suddenly dying during a meeting with Elizabeth on the first day of the U.N. General Assembly. Later, a “fake news” story surfaces claiming Elizabeth is responsible for the man’s death.

Elizabeth heads to Brussels to seek NATO’s support against Russia when it threatens to invade Bulgaria, but when France refuses to cooperate, it could threaten the alliance’s very existence. Also, Henry’s new government role has him dive into the Russia issue and turn to his former operative, Dmitri Petrov, for help; and as Nadine and Mike B’s relationship heats up, Elizabeth finds out information about her old friend that makes her question his loyalties on the third-season finale.